This invention relates to a snowmobile and more particular to an improved cooling system for the engine of a snowmobile.
Because of the unique arrangement and utilization of snowmobiles, the cooling system for the engine takes a form which is peculiar to this type of vehicle. For a variety of reasons, it is desirable to utilize a liquid cooled engine. This necessitates the utilization of one or more heat exchangers so as to exchange heat from the engine coolant to the atmosphere to maintain the desired engine operating temperature. Unlike automobiles, it is not practical or necessarily desirable to utilize a tubular type radiator having fins as are employed with other types of vehicle applications. Rather, the heat exchangers are generally formed from box-like housings through which a water path passes and which housings are formed with fins for heat exchange for the atmosphere. Because of the relative or less efficiency of this type of heat exchanger, it has been necessary to employ plural heat exchangers in order to obtain the desired engine temperature control.
Because of the relatively large drive belt and the desirability of avoiding too much airflow through the forward portion of the snowmobile, it has been the practice to mount a pair of heat exchangers one under each of the foot areas of the snowmobile frame. The foot areas of the snowmobile are formed generally from a sheet metal frame member that has an inverted U-shape. The foot areas extend outwardly from the lower ends of the inverted U-shape legs. By mounting the heat exchangers on the underside of these foot areas, some reinforcing can be obtained.
However, the positioning of the heat exchangers in this area adds weight to the outer perimeter of the sheet metal frame and thus, the frame actually may become weakened in a transverse direction.
It also has been the practice to employ either one transverse heat exchanger or a pair of transverse rear heat exchangers through which the liquid is circulated. These arrangements further complicate the conduits required for the cooling system, as may be best understood by reference to FIGS. 27 and 28 which show two prior art-type of constructions of the aforenoted type, respectively. These two views are schematic top plan views of the snowmobile cooling systems with the running components of the snowmobile removed in order to more clearly show the construction.
In each embodiment of the prior art, a transversely extending water cooled internal combustion engine, indicated generally by the reference character E, is placed at the front of the snowmobile. A pair of side radiators S1 and S2 are mounted are located under the foot areas at the side of the seating area in the snowmobile. These side heat exchangers S1 and S2 are of the double pass type in that coolant is entered into one end of each heat exchanger flows along the length of the heat exchanger, reverses direction and exits at the other side of the front of the heat exchanger.
In addition in one prior art construction as seen in FIG. 27, a transverse front heat exchanger F is provided. The engine E is provided with a coolant pump P that circulates the coolant through the cooling jacket of the engine through an inlet. The coolant that has passed through the engine cooling jacket is then discharged through a discharge D. This coolant then flows into the front end of the first side radiator S1 rearwardly, reverses and then flows forwardly.
The coolant is then discharged through an extending conduit in the direction shown in the arrows so as to the enter the front end of the other side heat exchanger S2. The flow then is along the length of this heat exchanger to the rear, reverses and then returns for discharge into one side of the front radiator F. The coolant then flows across the front radiator F and exits through a conduit to the pump P. The front radiator F may be either of a single or multiple pass type.
It should be apparent from this construction that substantial external conduits are required for the cooling system. In addition, the cooling system may not be provided with adequate surface area for cooling.
FIG. 28 illustrates the second type of prior art construction which has side radiators S1 and S2 and has a pair of rear radiators R1 and R2. With this type of system, the coolant discharged from the engine discharge D is again delivered to the front of the side radiator S1, flows rearwardly and then forwardly to exit through a crossover pipe extending across the front of the engine and into the front side of the second side radiator S2. This flow then flows rearwardly and forwardly. A discharge pipe carries the coolant from this radiator across the front of the engine and back to the front side of the first rear radiator R1.
An external pipe causes the coolant that is passed through the radiator R1 to pass through the radiator R2 and then back to the inlet of the pump. An expansion tank T is disposed in this circuit so as to accommodate variations in fluid volume under different temperatures of the coolant. Again, this system requires substantial external conduits.
It is, therefore, a principal object of this invention to provide an improved cooling system for a water cooled snowmobile engine.
It is a further object of this invention to provide an improved cooling system for the engine of a snowmobile wherein adequate numbers and positioning of heat exchangers may be employed for good cooling.
It is a still further object of this invention to provide a multiple heat exchanger arrangement for cooling a snowmobile wherein the number and length of the external conduits required to interconnect the various heat exchangers with the engine can be substantially reduced.
It is a still further object of this invention to provide an improved cooling system for a snowmobile wherein the heat exchangers are utilized in such a way so as to provide substantial reinforcing for the frame.